| AR & PA Transport Limited | Extraterritorial | 2014 |
| AR & RV Brown Limited | Transport & logistics | 2017 |
| AR Cars Ltd | Wholesale & retail | 2025 |
| AR Norwich Limited | Hospitality | 2026 |
| Ar-Razzaakh Ltd | Information & communication | 2025 |
| Araeb Parkes Ltd | Administrative & support | 2023 |
| Arago Technology Limited | Professional & scientific | 2010 |
| Arah WE DID IT Ltd | Financial services | 2022 |
| Arames Property Ltd | Real estate | 2025 |
| Arasaka Corporation Limited | Information & communication | 2021 |
| ARB Marketing and ID Services Ltd | Wholesale & retail | 2026 |
| ARB Recovery Norfolk Ltd | Wholesale & retail | 2026 |
| Arberg Ltd | Real estate | 2026 |
| Arbetb Ltd | Real estate | 2025 |
| Arbons Ltd | Construction | 2014 |
| Arborcare Tree Surgery (U.K.) Ltd | Agriculture & fishing | 2026 |
| Arborpro Tree Services Ltd | Administrative & support | 2018 |
| ARC (Norwich) Limited | Administrative & support | 2008 |
| ARC Home Innovation Ltd | Manufacturing | 2026 |
| ARC Homes Limited | Construction | 2019 |
| ARC Hospitality, Entertainment and Maintenance Ltd | Real estate | 2023 |
| ARC Offshore Solutions Ltd | Construction | 2014 |
| ARC OIL and GAS Consultants Ltd | Professional & scientific | 2019 |
| ARC Seven Communications Ltd | Professional & scientific | 2009 |
| Arcade OPS Limited | Wholesale & retail | 2026 |
| Arcana Softworks Ltd | Information & communication | 2023 |
| Arcane Developments Ltd | Real estate | 2026 |
| Arcane Property Investments Ltd | Real estate | 2022 |
| Arcane X Ltd | Real estate | 2026 |
| Arcanus Radiologic Ltd | Health & social care | 2022 |
| Arcara Group Limited | Financial services | 2026 |
| Arcate Ltd | Real estate | 2012 |
| Arcflow Limited | Professional & scientific | 2018 |
| Arch Glazing Ltd | Construction | 2018 |
| Archby Holdings Limited | Professional & scientific | 2012 |
| Archer VET Consultancy Limited | Education | 2011 |
| Archer Woodnutt Property Holdings Limited | Real estate | 2020 |
| Archers Butchers Limited | Manufacturing | 2012 |
| Arches Restaurant Ltd | Hospitality | 2016 |
| Archidite Limited | Professional & scientific | 2011 |
| Archie's Hardware Ltd | Extraterritorial | 2016 |
| Architectural Design & Planning Partnership Limited | Construction | 2016 |
| Architecture Inclusively Ltd | Professional & scientific | 2025 |
| ARCHITEKT23 Ltd | Professional & scientific | 2011 |
| Archive Holdings Ltd | Extraterritorial | 2022 |
| Archive Logistics Ltd | Transport & logistics | 1987 |
| Archive-Vault Limited | Other services | 2006 |
| Archived 43846 LLP | | 2010 |
| Archlm Ltd | Professional & scientific | 2012 |
| Archway Admin Limited | Administrative & support | 2015 |
| Archway Cards Ltd | Wholesale & retail | 2000 |
| Archway Court Management Limited | Hospitality | 1987 |
| Arcscribe Ltd | Information & communication | 2025 |
| Arctic Pipe Services Ltd | Manufacturing | 2023 |
| Arcturus Energy Services Limited | Professional & scientific | 2021 |
| Arcus Capital (Management) Ltd | Financial services | 2025 |
| Arcus Capital (Oakwood) Ltd | Financial services | 2019 |
| Arcus Capital Ltd | Financial services | 2013 |
| Arcus Resources Ltd | Other services | 2012 |
| ARD Advisory Ltd | Professional & scientific | 2023 |
| Arden Grange Limited | Wholesale & retail | 2015 |
| Ardencaple Enterprises Limited | Financial services | 2024 |
| Ardenco Limited | Manufacturing | 2002 |
| Ardey Ltd | Transport & logistics | 2024 |
| Ardizzone Tree Care Limited | Agriculture & fishing | 2026 |
| Area Property Investments Limited | Real estate | 2026 |
| Arena Building Supplies Limited | Wholesale & retail | 2007 |
| Arenafleet Limited | Extraterritorial | 2002 |
| Arenig Technology Solutions Ltd. | Information & communication | 2016 |
| Ares Locksmith Limited | Administrative & support | 2021 |
| ARF 2014 Limited | Real estate | 2014 |
| Arfat Kebab House Ltd | Hospitality | 2019 |
| Argeles Consultancy Limited | Professional & scientific | 2020 |
| Argent of London Limited | Wholesale & retail | 1996 |
| Argents Holdings Ltd | Financial services | 2021 |
| Argo Energy Ltd | Professional & scientific | 2026 |
| Argusync Ltd | Information & communication | 2023 |
| Argyl Ltd | Health & social care | 2019 |
| Arham Traders Ltd | Wholesale & retail | 2018 |
| Arhj Holdings Limited | Financial services | 2019 |
| Aristem Ltd | Professional & scientific | 2025 |
| Aristo Group Ltd | Professional & scientific | 2020 |
| Aristotle Centre for Excellence Ltd | Education | 2020 |
| Ariz+ Maaz Limited | Professional & scientific | 2019 |
| Arjay Services Glos Ltd | Construction | 2013 |
| ARK Creating Spaces Ltd | Real estate | 2023 |
| ARK Designs Ltd | Professional & scientific | 2026 |
| ARK Studio Limited | Professional & scientific | 2016 |
| ARK Studios Global Limited | Arts & recreation | 2019 |
| ARK Ventures UK Ltd | Education | 2012 |
| ARK Wildlife Management Ltd | Professional & scientific | 2026 |
| Ark-Haus Homes Ltd | Real estate | 2020 |
| Arka Services Limited | Construction | 2019 |
| Arkady Holdings Limited | Financial services | 2026 |
| Arkbite Limited | Administrative & support | 2025 |
| Arketype Consulting Ltd | Professional & scientific | 2023 |
| Arkha Non-Conventional Energy (Holdings) Limited | Energy | 2014 |
| Arlenne Ltd | Wholesale & retail | 2016 |
| Arlington Construction Ltd | Construction | 2022 |
| Arlington Park East Ltd | Real estate | 2021 |